Without knowing the details, such as game name and settings level, I'll focus on general laptop tips. Make sure Windows' power profile isn't in some battery preserving mode. Set it for maximum performance. Game on AC power, not battery power. Use a program, like MSI Afterburner, to monitor temperatures of CPU and GPU while you game. You want to make sure the laptop isn't getting too hot.
Also, are you saying you get exactly 120fps on every game? Are you using some form of vsync?